Endoscopic ultrasound (EUS) is a minimally invasive procedure to assess digestive (gastrointestinal) and lung diseases. It uses high-frequency sound waves to produce detailed images of the lining and walls of your digestive tract and chest, nearby organs such as the pancreas and liver, and lymph nodes.

When combined with a procedure called fine-needle aspiration, EUS allows your doctor to sample (biopsy) fluid and tissue from your abdomen or chest for analysis. EUS with fine-needle aspiration can be a minimally invasive alternative to exploratory surgery.

EUS techniques are also used in certain treatments, such as draining pseudocysts.

EUS is used to find the cause of symptoms such as abdominal or chest pain, to determine the extent of diseases in your digestive tract and lungs, and to evaluate findings from imaging tests such as CT scan or MRI.

EUS may help in the evaluation of:

Cancer of the colon, esophagus, lung, pancreas or stomach, and ampullary and rectal cancers

Evaluate abnormal findings from imaging tests, such as cysts of the pancreas

Guide drainage of pseudocysts and other abnormal collections of fluid in the abdomen

Permit precise targeting for delivering medication directly into the pancreas, liver and other organs

EUS is performed on an outpatient basis and is well-tolerated by most people.

You may not be a candidate for EUS if you have had abdominal surgery that changed your anatomy, such as Roux-en-Y gastric bypass.

EUS is generally safe when performed at a center with experience and expertise in the procedure. Your doctor will discuss with you the risk of complications from EUS, which may include:

Bleeding, especially if fine-needle aspiration is done

Infection

Tearing (perforation) of the intestinal wall or throat

Pancreatitis, if fine-needle aspiration of the pancreas is done

You can reduce your risk of complications by carefully following your doctor's instructions for preparing for EUS.

Signs and symptoms to watch for after your EUS include:

Fever

Chest pain

Shortness of breath

Black or very dark-colored stool

Difficulty swallowing

Severe or persistent abdominal pain

Vomiting

Call your doctor immediately or go to an emergency room if you experience any of these signs or symptoms.

Your doctor will give you specific instructions to prepare for your EUS. You may be asked to:

Fast before EUS, to make sure your stomach is empty.

Prepare your rectum, if EUS is being done in the rectal area. You may be asked to take a laxative or have an enema and to follow a liquid diet before the procedure.

Stop taking certain medications, such as blood thinners. Blood thinners may increase your risk of bleeding if fine-needle aspiration is performed during EUS. If you have chronic conditions, such as diabetes or high blood pressure, your doctor will give you specific instructions regarding your medications.

Plan ahead for your recovery, if you will be sedated before EUS. Most people who have EUS are given medication to relax them. Arrange for someone to drive you home after the procedure.

You likely will be given medicine to help you relax.

During EUS your doctor passes a thin, flexible tube (endoscope) through your mouth and through your digestive tract. A small ultrasound device (transducer) in the tube produces sound waves that create a precise image of surrounding tissue, including lymph nodes in the chest. The endoscope is then gradually withdrawn.

If you have fine-needle aspiration with EUS, your doctor will pass a second, curved device into your digestive tract. That device can guide a very slender needle to your lymph nodes and tumors or other abnormalities. The needle extracts fluid and tissue for analysis.

EUS with fine-needle aspiration generally lasts about an hour.

A specialist in digestive diseases (gastroenterologist) or lung disease (pulmonologist) with special training in EUS will interpret the EUS images. A doctor trained in analyzing biopsies (pathologist) will report the test results if you have fine-needle aspiration. Your doctor will discuss any important findings and next steps with you.

Expertise. The skills of the doctors performing the procedure and analyzing the results are critical to the success of EUS imaging and guided biopsy. Mayo has specialists with advanced training in EUS and pathologists who specialize in diagnosing cancers.

New ideas. Mayo researchers are working to improve EUS and explore further applications of the technique. You have access to the expertise of Mayo's clinician-researchers.

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Mayo Clinic works with hundreds of insurance companies and is an in-network provider for millions of people. In most cases, Mayo Clinic doesn't require a physician referral. Some insurers require referrals or may have additional requirements for certain medical care. All appointments are prioritized on the basis of medical need.

For appointments or more information, call the Central Appointment Office at 800-446-2279 (toll-free) 8 a.m. to 5 p.m. Mountain Standard Time, Monday through Friday or complete an online appointment request form.

Researchers at Mayo Clinic are working to improve EUS and explore further applications of the technique. Specific efforts involve determining risk factors for EUS of the lower digestive tract, the role of endoscopic ultrasound in lung cancer staging, and the lack of association between tumor recurrence and EUS with fine-needle aspiration.

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